There are many known containers for storing and cooking food, including microwavable bags for popping popcorn. Such bags typically have a microwave susceptor in one panel for absorbing microwave energy and heating the contents of the bag. Further, such bags typically have gusseted side panels which enable the bag to be folded flat for storage and shipment but which unfold and enable the bag to expand when the food inside the bag is cooked. These gusseted side panels usually terminate at folded end flaps at the opposite end corners of the bag, and in conventional bags these end flaps define interior pockets or shelves as the bag expands and the gusseted side panels unfold. These pockets or shelves then define areas into which uncooked food, especially unpopped kernels of corn, may migrate and be held away from the source of heat, whereby these pieces of food will remain uncooked. In a conventional popcorn bag, 9 grams or more of unpopped kernels may remain in the bag after the popcorn is cooked, at least partially due to the kernels migrating into the pockets or shelves defined by the corner flaps at opposite ends of the bag.
Attempts have been made in the prior art to solve this problem, as exemplified, for example, in U.S. Pat. No. 4,810,844, issued Mar. 7, 1989, to Alan R. Anderson; U.S. Pat. No. 5,044,777, issued Sep. 3, 1991, to Jeffrey T. Watkins, et al.; and U.S. Pat. No. 5,326,576, issued Jul. 5, 1994, to John C. Zuege. Anderson describes a system in which the bag is constructed to be stood on its side, with triangularly shaped corner sections 14 defined by bonding the panels of the bag together in the corners, Watkins provides diagonally extending adhesive patches 64-67 and 68-72 at opposite ends of the bag to close off the pockets or shelves that might otherwise be formed by corner flaps at opposite ends of the gusseted side panels, and, Zuege provides attachment means 24, 24' in the seamed area of bag closure means 26 at the open or top end of the bag to hold the gusseted side panels together and maintain the food to be cooked adjacent the heat enhancer to provide uniform and complete cooking of the food.
The microwave popcorn package described by Anderson departs from the usual "pillow" or "lunch bag" style most normally employed in that it does not incorporate gusseted side panels, and is constructed to stand on its side during cooking of food therein. To this end, the corners of the bag, at least at one side, are flattened and secured together so that they extend outwardly in opposite horizontal directions to help stabilize or support the bag on its side.
Watkins, et al. describe a popcorn bag of the more usual "pillow" style having gusseted side panels and an upper end that may be opened to dispense the popped popcorn. However, this package utilizes a large amount of adhesive to effect the seals at the top and bottom ends of the bags, especially the diagonal patches of adhesive that are incorporated to close the gusseted side panel flaps or pockets at opposite ends of the bag.
Zuege describes a microwave popcorn bag of essentially conventional construction, except for the attachment means 24, 24' provided between the gusseted panels at the upper end of the bag in the area of closure means 26. These attachment means, which may comprise patches of adhesive, are used to secure the upper end of the bag in the configuration shown in FIG. 4 prior to filling, and purport to close the pockets or shelves at the upper end of the bag during popping of the popcorn in the bag.
Consequently, a need exists for an inexpensive and effective way of preventing formation of the pockets or shelves defined by the corner flaps at the gusseted side panels of a bag used to cook food in a microwave oven, to avoid or minimize entrapment of food particles in such pockets which might otherwise form during cooking of food in the bag, thereby increasing the yield of food cooked in the bag as compared with the yield obtained in conventional bags.